This invention relates to a connection device for connecting an electronic equipment and a signal cable, and particularly to a connection device having a connecting plug and a connecting jack and adapted for connecting a signal cable to an electronic equipment by inserting the connecting plug into the connecting jack.
Conventionally, in order to connect a plurality of electronic equipments to enable transmission and reception of signals, a dedicated signal cable is used and a connector is used for connecting a signal cable and an electronic equipment. The connection device of this type connects the signal cable and the electronic equipment by usually inserting a plug or jack mounted at the end of the signal cable into a jack or plug provided on the equipment.
Recently, as a signal cable used for connecting various types of electronic equipments, not only an electric signal cable, which has been well known conventionally, but also an optical signal cable or the like for transmitting information by using light is used.
An equipment for transmitting information between electronic equipments by using light is described in the European Laid-Open Patent Application 0430107A2. A connection device which enables easy connection between a connecting plug and a connecting jack and easy disconnection thereof is described in the specification of the U.S. Pat. No. 4,540,236.
An exemplary connection device used for transmitting information between electronic equipments by using an optical signal cable will now be described.
In this connection device, a jack 103 is provided on the side of an electronic equipment 105, and a plug 102 to be inserted and fitted in the jack 103 is mounted on both ends of an optical cable 104, as shown in FIG. 1.
When the plug 102 is inserted into a receiving hole of the jack 103, a core 106 of the optical cable 104 provided at the center of the plug 102 faces an optical element 100 provided within the electronic equipment 105. The jack installed in the electronic equipment 105 is called receptacle.
Referring to FIGS. 2A and 2B showing schematic cross-sectional views of the structure of the plug and the receptacle, a typical connection state will be described.
A plug 102 shown in FIG. 2A has a substantially cylindrical plug body 111 mounted at the distal end of an optical cable 104, which is a signal cable for connecting a plurality of electronic equipments 105, and holding a core 106 of an optical fiber at the central axial core, and an unlocking member 121 fitted on the outer circumference of the plug body 111 so as to be movable in the axial direction of the plug body 111. As a ring-shaped engagement piece 114 is projected on the outer circumferential surface of the plug body 111 is situated in a void 122, the plug body 111 and the unlocking member 121 are movable with respect to each other in the axial direction of the plug 102 within the spatial range in the void 122.
As for a jack 103 installed on the equipment side, a tapered hole 136 to fit with a tapered portion 111a formed at the distal end of the plug body 111 is opened at the center, and the core 106 provided at the center of the inserted plug 102 and an optical element 100 installed in the equipment are maintained at predetermined positions and arranged to face each other at a constant distance from each other.
A plurality of lock members 131 for holding the plug 102 inserted in the jack 103 are housed in the jack 103. The lock member 131 is supported in the jack 103 via a pivotal point portion 135 and is supported to be rotatable about the pivotal point portion 135 into the direction orthogonal to the direction of inserting the plug 102. The lock member 131 has a press operator 134 projected at its center, and a plug engagement pawl 133 protruding toward plug 102 inserted in the jack 103 is formed at the right end in FIGS. 2A and 2B.
The plug 102 in this example is inserted into the jack 103 as the unlocking member 121 movable with respect to the plug body 111 is held by a hand. Therefore, when the plug 102 is inserted halfway in the jack 103, an abutment piece 127 protruding inside the unlocking member 121 is abutted against the engagement piece 114 of the plug body 111, as shown in FIG. 2B. That is, the unlocking member 121 is moved rightward in FIG. 2B relatively to the plug body 111.
As the plug 102 is inserted further into the jack 103 and the tapered portion 111a formed at the distal end of the plug body 111 is inserted and fitted in the tapered hole 136 provided at the center of the jack 103, the center of the core 106 is aligned with the center of the optical element 100 installed in the equipment. Thus, the insertion of the plug 102 in the jack 103 is completed.
When the plug 102 is inserted, the press operator 134 of the lock member 131 provided in the jack 103 is pressed by the unlocking member 121, and the plug engagement pawl 133 on the distal end side is rotated about the pivotal point portion 135 into the direction away from the inserted plug body 111, as shown in FIG. 2B.
As the plug 102 is further and fully inserted into the jack 103, the lock member 131 is rotated back to the inserted plug 102. The plug engagement pawl 133 is engaged with an engagement groove 124 formed at the distal end of the plug body 111, and the press operator 134 is engaged with a cam groove 123 formed at a halfway part of the plug body 111.
By being engaged with the engagement groove 124, the plug engagement pawls 133 hold the plug body 111 between them, and hold the inserting position of the plug body 111 to the jack 103, thus preventing detachment of the plug 102 when an external tension is applied to the optical cable 104.
In the case of extracting the plug 102 from the jack 103, the unlocking member 121 is moved leftward in FIGS. 2A and 2B along the axial direction of the optical cable 104. When the unlocking member 121 is moved leftward in FIGS. 2A and 2B, the press operator 134 provided at a halfway part of the lock member 131 is guided by the cam groove 123 to move to the outer circumferential surface of the unlocking member 121. The plug engagement pawl 133 of the lock member 131 is rotated about the pivotal point portion 135 into the direction away from the plug body 111, thus unlocking the plug body 111.
The junction part between the plug 102 and the jack 103 is the optical connecting part between the core 106 of the optical cable 104 and the optical element 100 inside the equipment. As the plug 102 is inserted, the core 106 of the optical cable 104 on the side of the plug 102 faces the optical element 106 on the equipment side. In order to minimize the transfer loss at the connecting part, the axial cores of the optical cable 104 and the optical element 100 must be aligned with each other with high accuracy and a constant distance must be maintained between the distal end surfaces of the optical element 100 and the optical cable 104.
The above-described structure for engagement and holding of the plug body 111 by the plug engagement pawl 133 of the lock member 131 is provided in order to prevent movement of the end surface of the optical cable 104 after the connection between the plug 102 and the jack 103 and to optimize the transfer characteristic of the optical cable 104.
In consideration of the structure, the position of the pivotal point portion 135 of the lock member 131 must be away to a certain extent from the center of the optical element 100, which is the axial core of the jack 103. As shown in FIG. 3, which is a schematic view of this state, the lock member 131 is rotated about the pivotal point portion 135 as the center of rotation and therefore the plug engagement pawl 133 moves along a locus indicated by X in FIG. 3. The distal end of the plug engagement pawl 133 has a gentle arcuate surface to avoid interference with the plug body 111. Therefore, an external force tends to generate a certain slack in the tapered portion, which is the junction between the plug 102 and the jack 103 and a change in the external tension may cause variance in the distance between the optical element 100 and the optical cable 104 and shift of the axial core. Moreover, if a large external force is applied to the optical cable, the plug 102 may fall out from the jack 103.
Meanwhile, in most cases, a connector provided on an electronic equipment is generally arranged at a position that cannot be easily seen by a user, for example, on the back side of the equipment, in order to keep good appearance of the electronic equipment. It is desired that the insertion/extraction of the connector can be easily carried out. Adding a fixing operation to the inserting/extracting operation is not desired by users.
The popularization of information equipments involves connection of a plurality of electronic equipments for use via signal cables such as optical cables. In this case, since many signal cables are used for connecting equipments. If, for example, one of the many signal cables is detached for a certain reason, it is difficult to search for that signal cable. Therefore, it is desired that the connecting part using a plug and a jack has a structure such that no detachment occurs even if a certain external force is applied to the signal cable.
In the above-described connection device, the distance in the direction of the axial core between the end surface of the optical cable and the optical element on the jack side tends to vary and the variance in the signal transfer characteristic cannot be disregarded. Therefore, characteristic problems arise.
In view of the foregoing status of the art, it is an object of the present invention to provide a connection device which can securely maintain a connecting state of a signal cable to an electronic equipment.
It is another object of the present invention to provide a connection device which can hold an accurate connecting position of a connecting plug to a jack and can maintain a good signal transfer characteristic.
A connection device according to the present invention includes a plug unit which has a connector plug provided at an end portion of a signal cable and an unlocking member supported on an outer circumferential surface of the connector plug so as to be movable in the axial direction of the cable and having a knob portion mounted thereon, and a receptacle unit in which the plug unit can be inserted and removed, wherein a lock member housed in the receptacle unit and adapted for being engaged with the connector plug to lock the plug unit is controlled by movement of the unlocking member in the axial direction of the cable via a cam portion provided on an outer circumferential surface of the unlocking member.
When the lock member used in this device is rotationally controlled by the movement of the unlocking member, the lock member is housed in a lock member housing portion provided in the receptacle unit, with its pivotal point position made movable.
The lock member for locking the connector plug is energized by an elastic member for providing an energizing force in a direction parallel to the axial direction of the cable and an energizing force in a direction perpendicular to the axial direction of the cable.
As the elastic member for energizing the lock member, a plate-like Z spring molded integrally with the lock member is used.
Alternatively, a Z spring formed by bending a thin plate in a Z-shape may be used as the elastic member.
The connector plug constituting the plug unit has a tapered portion provided as its distal end, the tapered portion being engaged with a tapered portion on the receiving side provided in the receptacle unit.
The lock member has a plug engagement pawl provided at its distal end, the plug engagement pawl being engaged with the connector plug. The plug engagement pawl is elastically displaceable.
An optical cable is used as the signal cable.